Bless

http://home.gna.org/bless/
Bless is a fast and customizable hex editor written in GTK#. It efficiently handles very large files and supports multiple undo-redo actions. There are also plans for the addition of a Lua-based scripting language for binary file manipulation.

The copyright and license notices on this page only apply to the
text on this page. Any software or copyright-licenses or other
similar notices described in this text has its own copyright notice
and license, which can usually be found in the distribution or license
text itself.